I have a django 1.6 site with i18n working. I can change the frontend language with a select box in the top of the template, but I don't know if there is a django app or trick to change the admin language, because it seems to store somewhere in session variable, and it keeps the first language I have used in the frontend.
In your settings.py just add 'django.middleware.locale.LocaleMiddleware'
to your MIDDLEWARE_CLASSES
setting, making sure it appears after 'django.contrib.sessions.middleware.SessionMiddleware'
.